This invention relates to a process of producing a semiconductor laser device and more particularly to a process of producing a semiconductor laser device exhibiting in at least three directions the effect of confining carriers.
Semiconductor laser devices have greatly decreased in the density of threshold current due to their so-called double heterojunction structure. However the dimension of semiconductor elements involved has imposed a limitation on the threshold current and therefore conventional semiconductor laser devices have been able to be usually operated with a current in the order of several hundreds of milliamperes. There have been generally known double heterojunction lasers comprising the semiconductor layer formed of a semiconductive material, normally gallium arsenide (GaAs) of N or P type conductivity narrow in an energy gap or a forbidden band width and sandwiched between a pair of N and P type semiconductor layers formed of a semiconductive material broad in a forbidden band width, normally of gallium aluminum arsenide (Ga.sub.1-x Al.sub.x As where x has a value less than unity and greater than zero). In double heterojunction lasers such as above described, light and carriers have been effectively confined in a direction perpendicular to the plane of the junction to permit light and carriers extremely high in density to be formed in the central GaAs layer. For this reason the threshold current of double heterojunction lasers have been reduced to be equal to or less than one tenth of that obtained by conventional homojunction lasers. However such double heterojunction lasers have exhibited no effect of confining light and carriers in the transverse direction of the junction.